If a high sugar diet is bad for you, why is fruit healthy?

This question originally appeared on Quora.

Daniel Layon, MS Candidate at Georgetown University explains why fruit is more than just a sweet snack:

Don’t make the mistake of looking at nutrition through a simple “macro-nutrient” perspective. Fruits and vegetables are not just “calories” or “grams of sugar”. They are nutritional packages that combine multiple difference micro- / macro- / phyto- nutrients.

Let me begin by demonstrating how fruits are good for you. In a classic study that examining the effects of the “Dietary Approaches to Stop Hypertension (DASH)”, Appel et al (1997) demonstrated, among other things, that a diet high in fruits and vegetables was a beneficial for lowering blood pressure. Closely examine the table below. Notice the highlighted area, which illustrates the relative number of servings of fruit per day in three different diets, a control diet, a high fruits and vegetables diet, and a combination diet.

The diet with higher fruits and vegetables did quite well in reducing blood pressure; though it is worth noting that the combined diet was superior to the fruits and vegetables diet.

A study by Joshipura et al (1999) demonstrated that an increased consumption of fruits and vegetables was associated with decreased incidence of ischemic stroke, as can be seen below.

An analysis of intake of specific food categories (fruits, vegetables, yogurt, etc) and their influence on weight loss was performed by the Harvard School of Public Health which found that increased consumption of fruits was associated with decreased total body weight:

NEJM 336: 2392 (2011).

Very quickly, I will address the sugar idea. Is pure sugar in large amounts bad for you? Yes. However, the sugar in fruit is not the same as the sugar that goes in your tea or soda. By this, I am not referring to the specific type of sugar , I am referring to the fact that the sugar in fruit comes with a hefty dose of fiber. Fiber attenuates the effect of sugar on insulin levels, which is why most fruits have a relatively lowglycemic index. In general, it’s better to eat things with a low glycemic load due to the effect on insulin and blood sugar of foods with high glycemic indices / loads:

(image courtesy of Dr. Sherman, GUMC).

So, in sum, I have yet to see a single study that convincingly demonstrates that fruit is not good for you. There may be an “upper limit” to its benefits, but it seems unlikely that fruit, even if consumed in large quantities, can cause harm.

Leave a reply